Lift truck



J. E. CLARKE Aug. 26, 1958 LIFT TRUCK l 6 Sheets-Sheet 1 Filed Aug. 2, 1956 6 Sheets-Sheet 2 '17a/wam MQ/91%; //ma;

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United States Patent O i LIFT TRUCK Jesse E. Clarke, Hinsdale, Ill.

Application August 2, 1956, Serial No. 601,753

13 Claims. (Cl. 214-130) This invention relates to a lift truck or the like more particularly of the type frequently known as a fork lift, for use in industrial plants, warehouses and similar establishments for material handling in the way of transporting objects such as boxes, cartons and the like from one location to another while changing their elevation, as,

for example, for unloading a delivery truck.

An important object of the present invention is the provision of a lift truck of this type in which vertical movements of the fork occur in a substantially linear vertical line at all times, the fork carriage being supported by an overhanging boom.

Another object is the provision of a low chassis truck so that the boom and with it the fork at the outer end of the boom may be superposed over `a delivery truck floor, for example, the tail-gate of the vehicle being disposed between the truck chassis and the boom. By means of this construction the fork may be advanced Well into the interior yof the delivery truck to receive its load and the lift truck may then be backed out until the fork clears the tail gate whereupon the fork may be lowered to bring the load to the ground. This eliminates the necessity of hauling the goods in the first instance from the far interior of the truck to the tail gate.

Another object of the. invention is the provision of means for maintaining the tine members of the fork approximately horizontal at all times and furthermore an arrangement whereby the tine members of the fork may be given a slightly downward inclination at their forward ends to facilitate insertion of the fork beneath the load.

Another object of the invention is the provision of hydraulic driving means for the truck associated with a gas engine and means whereby the hydraulic pump normally driven by the engine for driving the truck and elevating the boom may be used in reverse as a motor for starting the gas engine.

These and other objects and advantages will be apparent from the following description taken together with the accompanying drawings, showing an illustrative embodiment of the invention, in which drawings* Figure l shows a side elevational View of a lift truck embodying the present invention, alternative positions of the fork being shown in broken lines, the gas engine and hydraulic control levers being omitted for clearness of description;

Figure 2 is a plan view of the structure of Figure l;

Figure 3 is a View somewhat similar to Figure 1 but` on a slightly larger scale and being a view taken on a longitudinal section line, the gas engine and hydraulic control levers being shown;

Figure 4 is a plan sectiontaken on the line 4--4 of Fig. 3;

Figure 5 is an enlargedview of the truck drive and is a fragmentary section taken on the line 5-5 of Fig. 6;

Figure 6 is an end view of parts shown in Fig. 5 and being a view taken on the line 6-6 of Fig. 5;

Figure 7 is a plan section taken on a line 7-7 of Fia 6;

2,849,132 Patented Aug. 26, 1958 ICC -f-or the hydraulic fluid; and Figures 13 to 1S show an alternative valving arrangement.

Referring in detail to the illustrative construction shown in the drawings, 21 is the truck chassis which has legs 22 of box-beam construction extending toward the right, connected transversely by box-beam cross-member 23 and each leg terminating at its left-hand end in a podium 24 desirably of built-up construction and spaced apart to receive the mast column and its associated parts as presently described. The podiums 24 carry platforms 25 for accommodation of the operator by providing him a place to stand while traveling with the truck. The forward ends of the chassis legs 22 carry wheels 26 on axles 27 that are journaled in the ends of the chassis legs respectively. Between the podiums 24 is mounted a single dirigible wheel 2S that is lcarried on an axle 29 journaled in a vertical yoke 30 that is pivotally mounted by means of an'integral king pin 31in a boss 32 carried at the outer end of an angular overhanging support arm 33 that has an upright portion 34 that is secured at 35 between the podiums 24 to an angle cross bar 36 that is secured transversely between the podiums on the inner walls 41 thereof. The king pin 31 has rigidly connected to it at its upper end 37 as at 38 the hub 39 of a tiller or steering handle 40.

Pivotally footed in the podiums 24 on their inner walls 41 as by trunnions 42 is a box construction mast column 43 as shown in the drawing of a height approximately the length of the chassis that is formed of a pair of spaced upright beams 44 and a web plate 45 thus providing a rearwardly facing channel reinforced at vertical intervals by cross plates 46, beams 44 being inwardly offset at their upper ends from their lower ends 43a, as best seen in Fig. 6.

Connected to the mast 43 and also to the chassis 21 are a pair of toggle joints 47 that straddle the mast. Each toggle joint 47 includes a forward link 48 that is pivoted at 49 `on a rearward extension S0 of the cross beam 23 and a rear link 51 that is articulated with the mast 43 by the pivot pin 52 projecting laterally outwardly from the mast 43 at a predetermined distance above the pivot point 42 of the mast on the chassis. Links 48 and 51 are articulated with each other on pivot pins 53 that extend laterally outwardly at each side from the lower end of a reciprocable strut 54, this strut also being built-up construction having side walls 55 and a rear web 56.

Strut 54 extends upwardly in parallel relation with the mast 43 and at its lower end is supported by the pair of toggle joints 47 and connected at ythis lower end with the mast by the pair of toggle links 51. At its upper end the strut 54 is articulated as at 59 with the boom 60 which comprises a pair of parallel beams 61 held together at their outer ends by sleeved spacers 63 and 64 and at their rear ends pivoted respectively as at 65 to the upper end of the mast 43, the boom 61 thus straddling the mast 43 and the strut 54. A plate 62 between the beams just forward of the pivot 65 reinforces the boom at this end. The pivot pins 59 articulating the boom to the strut are located in a depending skirt portion 66 of each beam 61 ladjacent the proximal end of the boom and are spaced from the pvot 65 of the boom to the mast the same dis- 3 tance as the pivot 53 of the strut is from the pivot 52 of the links 51 on the mast. Thus the pivots 52, 53, 59, and 65 dene a parallelogram in all positions of the strut 54 with respect to the mast.

The strut 54l and toggle'joints 47 are reciprocablyv supported by a hydraulicy jack 67 that has a cylinder 68 and a plunger 69. Thev cylinder 68 is pivotallysupportedon rocker shaft 70 journaled in brackets 70aV that are advantageously supported bya V-channel 71 that is Xed trans.-

versely between the podium walls `at this location below the rocker shaft. The piston 69 is articulated as at 72 with the strut 54 intermediately of its length and substantially above the pivot 53 of the stru-t tothe toggle joints 47. Pivot 72 is journaled in a pair of brackets 74 carried onthe walls of the strut'54, the strut being of open construction to receive the jack between the sides.

Strut 54 projects above the boom 60 as at 76 and at itsl upper end carries jaws 76a to which are pivoted by the` pivot pin 77 ay stabilizer link 78. At its forward* end the stabilizer link 78 is articulated bypivot pin 79 with a pair of rearwardly projecting lobes 80 that are rigid with the upper end of main post 81 `of the fork carriage 82, the fork carriage and fork being generally L-shape and pivoted on trunnion 83 at the outer end of the boom 60 intermediately of the height of post 81. Trunnion 83 is carried in a T-formation 84 (Fig. 1l) formed integrally with the fork carriage post 81 and it provides a pivot for the boom members 61. At its outer ends trunnion 83- carries the fork uprights 85, the latter having rearwardly .projecting ears 86 (Fig. 9) in which the trunnion is rigidly secured by'nuts 87 passed onto the trunnion 83, the nuts having threaded Shanks 88 that enter threaded recesses in the outer faces of the ears 86 respectively. At their lower ends the fork uprights 85 are similarly connected by ears 91 to arms 90 of the post 81 by nuts 91a. Rigid with the uprights 85 are the forwardly extending tines 92 respectively. As clearly shown in the drawings (compare Figs. 1, 3, 8 and 10) the stabilizer link 78 maintains the carriage post or arm 81 upright and the tines 92 horizontal, or substantially so, in all positions of the boom.

Reverting to the truck drive, as best seen in Figs. 6 and 7 the dirigible rear wheel 28 has pinned thereon as at 94 therewith on its axle 29 a relatively large gear 93, within the yoke mounting 30. Meshing with the gear 93 is a pinion 95 that is pinned as at 96 on a stub shaft 97 above the wheel 28 and that has pinned thereon `at its other end as yat 97a a gear 98 that in turn is in mesh with a pinion 99 that is xed on the output shaft 100 of a hydraulic fluid motor 101. The hydraulic fluid motor 101 is rigidly mounted by brackets 102 on the leg 103 of the yoke 30, the motor 101 having the usual intermeshing lluid actuated gears 104 (Fig. 12). The motor 101 has inlet 105 and outlet 106 for the usual hydraulic fluid pipes later referred to.

The hydraulic circulating system is shown in Fig. 1'2 as well as the gas engine 107 here illustrated asl the prime mover in this instance. The gas engine by its output shaft 107a drives the hydraulic fluid pump 108 that at times is used as a hydraulic motor. When the pump 108 is in operation as a pump, driven by the engine 107, hydraulic fluid is drawn from the reservoir 109 through the check valve 110 and iluid line 111 and delivered under pressure to fluid line 112 in which is a manifold or junction 113. From junction 113 a portion of the iluid under pressure passes through the'check valve 115 in the line 114 and into the accumulator 116 where it acquires a pressure build-up as is well known in the art. Another portion of the iluid under pressure passes from the junction 113 to the line 117 in which there is arelief valve 118 and back to the reservoir 109. Line 118a connects into the pump 108 and the line 117 between the relief valve 118 and the reservoir to permit drainage from the pump back to the reservoir. Still another portion of the uid under pressure passes from junction 113 to the'line 119 and up to the valve 120, which, in one position, permits oil to pass to the line 121 and to the valve 122, and to the return line 123 back to the reservoir, thus permitting constant circulation when the valves 120 and 122 lare in neutral position, as shown in Fig. 12.

When it is desired to actuate the hydraulic jack 67 to extend the piston 69 upwardly, the valve 120 is given one-quarter clockwise turn from the position thereof shown in Fig. 12, to disconnect the line 119 from the line 121 and connect it with the line 124 that leads at 125 into the proximal end of the cylinder 68 thus causing the piston 69 to move upwardly under the iluid pressure. If it be desired to deliver hydraulic fluid to the motor 101 the valve 120 is left in the position in which it is shown in Fig. 12 and the open center peripherally recessed valve 122 is given a partial turn counter-clockwise from the position in which it is shown in Fig. 12 and thereupon lluid under pressure is delivered from the line 121 to the line 126 that leads into. the inlet 105; of the iluid motor 101 that drives the truck rear wheel 28,. the return line 127 connecting the low pressure side of the motor 101 with the return line 123 for the fluid. back to the reservoir 109. For reverse action of the motor 101 to back the truck, the valve 122 is given a partial turn clockwise, thereupon leading fluid from line 121 to line 127, through the motor in the reverse direction, and back through lines 126 and 123.

Valves 120 and 122 are controlled by hand levers 128 and 129 respectively which are conveniently carried on a pedestal 130 suitably mounted on chassis 21 and which may also provide a housingr for the reservoir 109 and accumulator '116. The hand levers 128 and 129 are thus conveniently located so as to be readily accessible to an operator from his position on the adjacent podium 24 at which position he is also within reach of the tiller 40 by which the rear wheel 28 may be rotatedl on its vertical axle 31 tosteer the truck.

It will be understood that operation of the fluid jack 67 by the hydraulic iluid need be only in one direction, that is, to extend the piston 69 to raise the boom 60, and that retractive movement of the piston occurs under the influence of the weight of the boom and the fork carriage when the pressure is relieved from the cylinder 68. When it is desired to lower the boom, the valve 120 is given another quarter turn clockwise from its position shown in Fig. l2, to connect line 124 with return line 123. At this time relief valve 118 permits pressure built up in the line 119 toA be dissipated back to the reservoir 109 through the line 117'.

The `arrangement just shown is such that the valve 120 can only be effectively actuated when they truck is standing still, and conversely the valve 122 can only be effectively actuated to drive the truck when the boom 60 is not being raised or lowered and the valve 120 is in neutral position shown in Fig. 12.

The reversible pump motor 108 is carried on abrackct 108a suitably secured to the cross beam 23 in' appropriate location for connection with the output shaft 107:1 of the engine 107. The engine 107 is shown securely mounted as by bolts 131 on a. platform 131a extending between the legs 22 of the truck chassis, and the engine may have a pulley 132 on its shaft by which the engine may be started if desired. However means are here shown for starting the engine by the hydraulic pressure. For starting the engine 107 by means of the hydraulic lluid, the foot operated or treadle valve 133 is provided which when pressed upon by the foot of the operator, against its inherent resilience, admits fluid pressure from the accumulator 116 to the line 135 and thus to the low pressure side of the pump 108 which thereupon becomes the high pressure side and converts the pump into a fluid motor to turn the shaft 107a of the engine thus starting the engine. It is to be understood that the gas engine 107 here shown illustrates oneform of prime mover that may be employed and that the truck could be adapted for electrical operation, for example, by batteries, if that were desired.

The fluid lines shown it; Fig. 12 may be suitably carried on the truck chassis in a manner which is well known to the art and need not be here specically shown.

It will be understood from the drawings that boom and fork carriage are movable from the position thereof shown in full lines in Fig. l, and also shown in Fig. 3, to their lowermost position as shown in broken lines in Fig. 1 and also in Fig. l0, to pick up a load, and that when the boom and fork carriage are moved from their lowermost position to their uppermost position as shown in broken lines Fig. 1, and also as shown in Fig. 8, to elevate the load, the forkcarriage moves by translation in a substantially linear vertical line, as indicated at A in Fig. l,

Travel of the fork carriage in a substantially linear vertical line is accomplished by the rearward and forward tilting movement of the mast 43 under the influence of the strut 54 and toggle joints 47, actuation of the strut 54 being accomplished by extension or retraction of the piston 69 of the hydraulic jack 67. When the boom is moved downwardly as shown in Fig. 10, the mast is tilted forwardly by the break of the toggle joints 47 thus shortening the distance between the pivot pins 49, on the truck chassis, and S2, on the mast, which shortening pulls the mast forwardly on its pivot 42. This forward tilting movement of the mast is just suiicient to compensate for the tendency of the boom, rotating on its pivot 65 on the mast, to describe an arc. The result is that the fork moves downwardly in a linear line. Similarly, when the strut 54 is moved upwardly by extension of the piston 69 of the jack, the toggle joints 47 are first brought back to a straight line condition as shown in Fig. 1 which tilts the mast rearwardly again, and then, as the strut continues to move upwardly to the position shown in Fig. 8, the toggle joint is broken upwardly, again reducing the distance between the pivot points 49 and 52 and drawing the mast again into a forward tilted position which compensates for the tendency of the fork carriage to describe an arc on its pivot 65 on the mast and keeping the fork to the straight linear vertical line A.

Since the pivot points 59, 77, 79 and S3 dene a ligure which is not a parallelogram but is rather a frustum of a triangle, the tines 89 are maintained substantially horizontal at -all times although in the lowermost position of the fork carriage, the tines are given a slightly downward inclination at their outer ends7 as shown in Fig. 10v

to facilitate insertion of the tines under a load. This is accomplished by making the distance between pivot pins 79 and 83 slightly longer than the distance between pivot points 59 and 77.

The fork carriage S2 in its lowermost position is advantageousl'y received between the ends of the legs 21 as best seen in Fig. 2, the chassis having a somewhat U- shape.

In the arrangement shown in Figs. 13 to 15 inclusive, valving means are illustrated by which the boom and drive may be independently operated separately or at the same time. Here the high pressure line 119 leads into the open center valve 122:1 which is a four-way valve having three positions, the neutral position being when the valve is in the position shown in Fig. 13, connecting the line 119 with the line 121 through its open center. When it is desired to drive the luid motor 101 in one direction, the valve 122:1 is placed in the position shown in Fig. 14 at which time iluid in the line 119 instead of passing directly into the valve 122:1 enters line 1190. through check valve 119b to connection 119a and from then through line 119C to line 122d, through a peripheral recess in valve 122g provided in the hollow valve element 122f, to line 127, through the motor 101, back through the line 126 through the peripheral recess provided in the valve 122g by the hollow valve element 122g, to line 122e and through line 123a and line 123 back to the reservoir. When it is desired to reverse the motor 101, the valve 122a is placed in the position shown in Fig. 15 at which time fluid under pressure in the line 119e passes through line 122e, through the peripheral recess provided in valve 122a by the valve element 122g to line 126, through the motor 101 in the reverse direction, back through the line 127 through the peripheral recess provided in Valve 122er by the valve element 122)c to the line 122b and thence to line 123g and through line 123 to the reservoir. The valve elements 122f and 122g to each side respectively of the open center of the valve 122a are partially cylindrically recessed on their peripheral faces to provide communicating recesses respectively for the lines connected to the valve as shown and just described.

When the valve 122a is in neutral position, as when the truck is standing still, and as shown in Fig. 13, fluid under pressure from the line 119 passes through the open center or valve 122a, through the line 121 and through the open center valve 120a which is for controlling the jack 12S. In Fig. 13 the valve 120g is shown in full lines in neutral position, permitting return ow of the fluid through valve 120a to line 123 and back to the reservoir. Valve 120a is a three-way valve with three positions. If it be desired to raise the jack 125, valve 120a is given a quarter turn clockwise from the position shown in full lines in Fig. 13 so that the peripheral solid valve elements 120e and 120b of the valve 120e shut oif the valve from the lines 121 and 123. At this time fluid under pressure is bypassed through the lines 119d and line 119e to the line 124 to raise the piston of the jack. If at the same time it be desired to move the truck, the valve 122a may be placed in either of the positions shown in Fig. 14 or Fig. 15 at which time a part of the iluid under pressure passes from the line 119d to the line 119e` and then through the line 122:1 or through the line 122e to the valve 122a depending upon the position of the valve 122a for forward or reverse movement of the truck. At any time when it is desired to lower the jack 125, the valve 120a is placed in the position where its solid valve elements 120e and 120b are obliquely disposed as shown in other dotted lines in Fig. 13 at which time the valve 120g places the line 124 and the low pressure line 123 in communication.

The letter A may designate a valve panel or housing for the valving mechanism just described.

In the case of either the valving arrangement shown in Fig. 12 or that shown in Fig. 13, the motor 101 can act as a brake for the truck drive. As the valve 122 or the valve 122a, as the case may be, moves from one of the drive positions to the neutral position shown respectively in Figs. 12 and 13 the lines 126 and 127 are cut off from the valve and the motor 101 then acts as a pump, by reason of the fact that since the truck is still in motion the gears 104 are rotating and are attempting to drive the fluid either from the line 126 to the line 127, or vice versa, depending upon the direction of movement of the truck, Since the fluid cannot move, slippage of the gears 101 occurs past the uid, thereby creating friction which brings the truck to a stop by a fast but smooth and non-jarring action.

An important result of the present invention is that the fork carriage can travel its full vertical range without the need for actuating a secondary assembly such as a telescoping mast which would restrict the rise in covered trucks, elevator cars or under low ceilings, this feature, which has not heretofore been achieved in fork lift designs, being known in the industry as free lift.

Another yimportant result is that the weight of the vehicle is substantially reduced to approximately 50% of that common in conventional lift truck design, this being accomplished by transferring functional lifting elements from their conventional position to a position at the rear of the vehicle where they serve as compensating Weight or balance for the overhanging load on the fork. In conventional design, the moment of the overhanging load andthe lifting elements adjacent the front of the vehicle must be balanced by heavy counterweights at the rear thus resulting in a service weight of approximately double that of the present invention for comparable capacity.

Braking of the truck of the present invention is accomp lished automatically when the operator moves the control handle from the operating position back to neutral thus closing the escape passage for the hydraulic fluid from the drive motor and imposing a braking force on the wheels without the necessity for an external brake.

So constructed and arranged, there is here provided an improved lift truckV that incorporates the advantages of an overhanging boom and a low-slung chassis while providing the unique further advantages of a .lift fork or the like that raises and lowers by substantially translatory motion on an approximately linear vertical line, so as to maintain a practically uniform distance from, say, the tailgate of a delivery truck when the lift fork moves vertically, or, similarly, from the edge of a platform or stack of piled boxes or the like, providing a desirable elevator effect. At the sarne time, a slight downward tilt may be provided for the distal ends of the fork, that facilitates entry of the fork under the load.

The invention is not intended to be limited to details of construction here shown for purposes ofexemplification thereof, and, furthermore, it may not be essential in all applications of the invention to use all features thereof conjointly, since various combinations and subcombinations may at times be advantageously employed.

One practical embodiment of the invention having been illustrated, pursuant to the statutes, such changes, including modifications or additions, may be made asnfall within the scope of the appended claims without departing from the invention.

What is here claimed is:

1. A lift truck, comprising, a mobile chassis, a `mast pivoted on the chassis, a boom pivoted on the mast overhanging said chassis, a strut pivoted on the boom forwardly adjacent the mast, said strut extending aboverthe boom, an L-shape member pivoted on the boom at its outer end, said member having an arm extendingabove the boom, a stabilizer link above the boom articulated with` the strut and with said arm, a pair of toggle joints articulated intermediately respectively with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut, hydraulic means carried by the truck for reciprocating the strut vertically, and propulsion means for the truck, whereby the outer end of the boom moves in a substantially linear vertical path and the base of the L-shape member is maintained approximately horizontal.

2. A lift truck, comprising, a body chassis, a mast pivoted on the chassis, a boom pivoted on the mast overhanging said chassis, a strut pivoted on the boom forwardly adjacent the mast, a toggle joint device articulated intermediately with the lower end of the strut and at its ends with the chassis and mast rearwardly and forwardly of the strut respectively, and power means for reciprocating the strut, the pivotal connections of the boom to the mast and strut and of the rearward link of the toggle joint to the mast and strut defining a parallelogram whereby the outer end of the boom moves in a substantially linear vertical path.

3. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis, aboom pivoted on the mast overhanging the chassis, a strut pivoted on the boom forwardly adjacent the mast, said strut extending above the boom, an L-shape member pivoted on the boom aty its outer end, said member having an arm extending above the boom, a stabilizer link articulated above the boom with the strut and said arm, a toggle joint device articu-` lated intermediate with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut respectively, power means for reciprocating the strut, and propulsion means for the truck.

4. In a lift truck comprising a mobile chassis, wheels for saidy chassis, a'mast pivoted on said chassis, a boom pivoted on the mast overhanging said chassis, a load receiving carriage at the outer end of the boom, a strut pivoted on the boom parallel with the mast, a link connecting the mast and strut and maintaining the mast and strut parallel means including said strut interconnecting said mast and boom for removing the carriage in a substantially linear vertical line during lowering and raising of the boom, said mast tilting forwardly and rearwardly therefor with the strut, and means maintaining.

the carriage approximately horizontal by a translating movement.

5. ln a lift truck of the class described, a mobile chassis, a fork carriage, a mast at the rear of the chassis,.

a boom pivoted on said mast and extending toward the forward end of the chassis above the latter, said fork.

carriage being mounted on said boom to project over the forward end of the chassis, a strut pivoted on the boom forwardly of the mast, a link connecting the mast and strut, means acting on said strut for pivoting the boom to move the fork carriage from a position below and forward of the chassis to a position forward of the chassis and above the mast including means for causing the fork carriage to have translatoryy movement in a substantially straight vertical line from one said position to the other.

6. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis adjacent the rear end thereof, a boom pivoted on the mast forwardly overhanging the chassis, a strut pivoted on the boom forwardly adjacent the mast, a toggle joint device articulated intermediately with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut respectively, power means for reciprocating the strut, and propulsion means for the truck, said means for reciprocating the strut including a hydraulic jack having a cylinder and piston, one end of the jack being pivotedy to the chassis and the other end thereof being pivoted to the strut above the pivot of the strut to the toggle joint.

7. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis, a boom pivoted on the mast overhanging the chassis, a strut pivoted on the boom forwardly adjacent the mast, the pivotal connection of the boom to the strut being below the pivot of the boom to the mast in the horizontal position of the boom, a toggle joint device articulated intermediately with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut respectively, power means for reciprocating the strut, propulsion means for the truck, and a load receiving carriage at the outer end of the boom.

8. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis, a boom pivoted on the mast overhanging the chassis, a strut pivoted on the boomforwardly adjacent the mast, a toggle joint device articulated intermediately with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut respectively, power means for reciprocating the strut, and propulsion means for the truck, the mast tilting slightly rearwardly in the horizontal position of the boom and tilting slightly forwardly on its pivot with the chassis on vertical movements of the boom.

9. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis, a boom pivoted on the mast overhanging the chassis, a strut pivoted on the boom forwardly adjacent the mast, said strut extending above the boom, a load member having an arm extending above the boom, a stabilizer link articulated above the boom with the strut and said arm, ,the pivotal connection of the boom to the strut and arm and of the stabilizer link to the strut and arm defining a frustum of a triangle, a toggle joint device articulated intermediately with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut respectively, power means for reciprocating the strut, and propulsion means for the truck.

10. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis, a boom pivoted on the mast overhanging the chassis, a strut pivoted on the boom forwardly adjacent the m'ast, an L-shaped member pivoted on the boom at its outer end, means maintaining the L-shape member vertical in various positions of the boom, a toggle joint device articulated intermediately with the lower end of the strut and at its ends with the mast and chassis rearwardly and forwardly of the strut respectively, power means for reciprocating the strut, and propulsion means for the truck, wherein the chassis is of U-form having a head portion and a pair of legs, and wheels are mounted at the ends of the legs respectively, and a single dirigible wheel is mounted at the head.

11. A lift truck, comprising, a truck chassis, a mast pivoted on the chassis, a boom pivoted on the mast overhanging the chassis, a strut pivoted on the boom forwardly adjacent the mast, said strut extending above the boom, an L-shape member pivoted on the boom at its outer end, said member having an arm extending above the boom, a stabilizer link articulated above the boom with the strut and said arm, a link articulated with the strut and with the mast, power means for reciprocating the strut, and propulsion means for the truck, wherein the chassis is of U-form having a head portion and a pair of legs, and wheels are mounted on the end of the legs respectively and a single dirigible wheel is mounted at the head, and wherein the L-shape member in its lowermost position is received between said legs.

12. In a lift truck of the class described, a chassis, a mast carried on the chassis adjacent the rear end thereof, a boom pivoted on the mast overhanging the chassis, a strut pivotally depending from the boom forwardly adjacent the mast, a link articulated with the mast and the strut, elevating means for the boom connected at one end with the chassis and at its other end with the strut, said elevating means including an extensible and retractable element for moving the boom pivotally on the mast in a vertical plane through the intermediation of the strut, and means for actuating said element.

13. A lift truck of the class described, comprising a longitudinally `elongated chassis, a vertically elongated mast pivoted on said chassis at the rear end thereof, a boom carried on the mast at the upper end thereof overhanging the chassis and extending forwardly thereof, links interconnecting the chassis, mast and boom adjacent the rear end of the chassis, and power means including said links for moving the boom in a vertical plane, whereby to provide an unobstructed space between the chassis and boom.

References Cited in the le of this patent UNITED STATES PATENTS 1,185,630 Carr June 6, 1916 1,346,914 Sauvage July 20, 1920 2,258,160 Nardone Oct. 7, 1941 2,372,220 -Mork Mar. 27, 1945 2,471,364 Weber May 24, 1949 2,556,378 Sisson June 12, 1951 2,643,779 Hamlin .Tune 30, 1953 2,789,648 Huffman Apr. 23, 1957 UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No., 29849,l32 August 269 3958 Jesse E o Clarke It is hereby cer-bif-ied that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column '75, line 759 for n'termedate" read intermedately u; column 87 line ll, for "removing" read moving o Signed and sealed this 28th day of' October 1958.,

(SEAL) I Attest:

KARL Ho AXLINE Attesting Oiicer ROBERT C. WATSON Commissioner of Patents 

